The factors that predicted the initiation of cholesterol-lowering drug therapy were selected by stepwise procedures from among the following baseline variables: the continuous variables of age, total cholesterol level, LDL cholesterol level, HDL cholesterol level, triglyceride level, creatinine level, body weight, body mass index (measured as the weight in kilograms divided by the square of the height in meters), alcohol consumption (grams per week), number of CHD risk factors, number of instrumental activities of daily living performed with difficulty (range, 0-6), and date of entry in the CHS cohort; the binary variables of sex, prevalent CHD, diabetes, hypertension, current smoking, family history of premature CHD, and race (white vs nonwhite); and the categorical variables of education (<grade 12, high school or vocational school, and college graduate or professional education), family income (<$5000, $5000-$7999, $8000-$11,999, $12,000-$15,999, $16,000-$24,999, $25,000-$34,999, $35,000-$49,999, and ≥$50,000), and clinic site. Seven of these variables were included as time-dependent variables: total cholesterol, LDL cholesterol, and HDL cholesterol levels were updated once for members of the original cohort in the third year of follow-up when the results of new tests became available; prevalent CHD, diabetes, hypertension, and instrumental activities of daily living were updated in each year of follow-up. Prevalent CHD and diabetes in each year of follow-up were defined cumulatively as CHD and diabetes at any time during the previous study years. Hypertension and difficulties with instrumental activities of daily living were updated in each year of the study with the most recent data. Stepwise procedures that included the female subjects only were also performed including estrogen use as a time-dependent variable in addition to the variables described earlier.